1. Field of the Invention
The present invention relates to a method for controlling the drive of an actuator of an active vibration isolation support system that includes an elastic body receiving a load from a vibrating body, a liquid chamber having a wall of which at least a part is formed by the elastic body, a movable member for changing the capacity of the liquid chamber, and an electromagnetic actuator for driving the movable member.
2. Description of the Relevant Art
Such an active vibration isolation support system is known and disclosed in Japanese Patent Application Laid-open No. 10-110771.
This active vibration isolation support system calculates a fixed period drive signal based on a reference signal that is output every time a crankshaft rotates through a fixed angle and a residual vibration signal that is transmitted from an engine to a vehicle body frame via the active vibration isolation support system, and feedforward control of the actuator is carried out based on this drive signal.
Conventionally, as shown in FIG. 6, in the case where the amount of lift of the actuator of the active vibration isolation support system is controlled so as to change with a sinusoidal wave form having a fixed period, a proportion of a constant voltage that is supplied to the actuator driver is regulated so as to be converted into thermal energy, and the remainder of the voltage is applied to the actuator thus giving a current with a sinusoidal wave form.
However, if the above-mentioned method is adopted not only is there the problem that the actuator driver generates heat thus requiring cooling, but there is also the problem that a proportion of the electrical energy is wasted as thermal energy in the driver thus increasing power consumption.
The present invention has been conducted under the above-mentioned circumstances, and it is an object of the present invention to allow the waveform and the period of the lift of an actuator of an active vibration isolation support system to be freely controlled while avoiding the generation of heat in the actuator driver and the corresponding increase in the power consumption.
In order to achieve the above-mentioned object, in accordance with the invention according to a first aspect and feature of the invention, there is provided a method for controlling the drive of an actuator of an active vibration isolation support system that includes an elastic body receiving a load from a vibrating body, a liquid chamber having a wall of which at least a part is formed by the elastic body, a movable member which changes a capacity of the liquid chamber, and an electromagnetic actuator which drives the movable member, the method comprising the steps of setting a large number of consecutive micro time regions, carrying out duty control of voltage that is applied to the actuator in each of the micro time regions, and setting, via a fixed number of consecutive micro time regions in which changes of duty ratio form a defined pattern, a period of a current that drives the actuator.
In accordance with the above-mentioned arrangement, by carrying out duty control of the voltage that is applied to the actuator individually in each of the large number of consecutive micro time regions, the waveform of a current that is applied to the actuator, that is to say, the waveform of the lift of the actuator can be set freely and, moreover, by changing the number of consecutive micro time regions in which changes of the duty ratio form a defined pattern, the period of the current that drives the actuator, that is to say, the period of the lift of the actuator can be set freely. Furthermore, since electrical energy is not wasted as thermal energy in the actuator driver, the problems of heat being generated in the driver and the power consumption increasing can be avoided.
An engine E of an embodiment corresponds to the vibrating body of the present invention, a first elastic body 14 of the embodiment corresponds to the elastic body of the present invention, and a first liquid chamber 24 of the embodiment corresponds to the liquid chamber of the present invention.